1. Field of the Invention
The present invention relates to a mucous membrane resection instrument for use in an endoscope (hereinafter referred to as “endoscopic mucous membrane resection instrument”), which sucks a mucous membrane in a substantially cylindrical cap attached to a distal end of an insertion portion of an endoscope, thereby forming a polyp-like projection portion, and resects a proximal portion of the projection portion using a diathermic snare, and to a method for the mucous membrane resection.
2. Description of the Related Art
In recent years, endoscopic mucous membrane resection for resecting a mucous membrane of a target part is performed using an endoscope without ventrotomy, thereby treating an early cancer at the esophagus or stomach. Jpn. U.M. Appln. KOKAI Publication No. 6-75402 (Patent Document 1) and Jpn. Pat. Appln. KOKAI Publication No. 2001-275933 (Patent Document 2) disclose methods wherein an endoscope and a diathermic snare are used in combination. In these methods, a substantially cylindrical hood is attached to a distal end of an insertion section of the endoscope. A flange-like projection (claw portion), which protrudes inward, is provided on the inner peripheral surface of the distal end portion of the hood.
Further, the diathermic snare includes a flexible sheath, an operation wire, and a snare wire. The operation wire is inserted in the flexible sheath so as to be advanceable and retreatable. The snare wire is coupled to the distal end of the operation wire. The snare wire is received in the sheath so as to be advanceable and retreatable. The snare wire has a loop portion that is broadened in a substantially circular or oval loop shape when the snare wire is advanced from the sheath.
When the diathermic snare is used, it is inserted in the channel in the endoscope. The diathermic snare is extended through the channel of the endoscope to the distal end side of the endoscope, and the diathermic snare is projected forward from the channel of the endoscope. Then, a work is conducted to set the loop portion of the diathermic snare in the state in which the loop portion is disposed along the flange-like projection portion on the inside of the hood (hereinafter this work being referred to as “looping work”). In this state, a target mucous membrane to be resected is sucked in the hood. At this time, the mucous membrane sucked in the hood is swollen in a hemispherical polyp shape. A proximal end portion of the swollen part of the mucous membrane sucked in the hood is strangulated by the diathermic snare and resected with electric power supplied to the snare.
Jpn. Pat. Appln. KOKAI Publication No. 2002-45369 (Patent Document 3) discloses a hood for an endoscope. A cap section is detachably attached to a distal end portion of the endoscope. A flexible tube for introducing a treatment instrument is provided along an insertion portion of the endoscope. A distal end portion of the flexible tube is coupled to the cap section. A diathermic snare is inserted in advance in the flexible tube. A loop portion of the diathermic snare is fixed to a projection portion within the cap section by an adhesive.
In the treatment instruments of Patent Document 1 and Patent Document 2, the hood along with the endoscope is inserted in the body cavity in advance. In this state, the diathermic snare is inserted in the channel in the endoscope, and a work for disposing the loop portion of the diathermic snare within the cap section of the hood (hereinafter referred to as “looping work”) is performed.
In the technique of Patent Document 3, the loop portion of the diathermic snare is fixed in advance to the projection portion within the cap section by means of an adhesive. This makes it possible to omit the time-consuming looping work during the treatment for endoscopic mucous membrane resection. However, in the case of performing endoscopic mucous membrane resection, when a target to-be-resected mucous membrane is large, it is not possible to suck the entire target mucous membrane into the cap section of the hood at a time. To cope with this problem, the large target part is divided into a plurality of portions and the divided portions are resected (hereinafter referred to as “divisional resection”). In the case of performing the divisional resection of the large target part, the same treatment procedure (the aforementioned endoscopic mucous membrane resection) is repeated several times.